Add install script

[pawamoy]

sudo make install or sudo ./install.sh

• check if python3 is available, if not, exit with message
• check if virtualenv is available, if not install with apt-get install -y python3-virtualenv
• create the virtualenv somewhere, install the requirements
• create a script as /usr/bin/run-shell-history or else, with the right env vars
• output a message to tell user to source shellhistory.sh at startup (pastable line)

Also write an uninstall script:

• delete the virtualenv
• delete the run script